In conventional networks, a carrier bandwidth is associated with a particular carrier frequency. Within an overall system bandwidth, there might be multiple carriers, each having a respective carrier bandwidth. Within each carrier bandwidth, respective guard bands are defined at the low frequency end and at the high frequency end to achieve channel separation between adjacent carriers. Guard bands are also defined between sub-bands on a single carrier. Throughout this description, reference is made to sub-bands of a single carrier. These can also be referred to as bandwidth parts or bandwidth partitions.
In wireless communications networks such as Long-Term Evolution (LTE) networks, Orthogonal Frequency Division Multiplexing (OFDM) transmissions use a 15 kHz spacing between two adjacent subcarriers for most applications. A 7.5 kHz subcarrier spacing was proposed for dedicated evolved Multimedia Broadcast Multicast Service (e-MBMS) service. A given transmitter transmits using one subcarrier spacing or the other. Resource block (RB) channelization involves defining resource blocks as the unit of allocation. In LTE, a respective fixed channelization is defined for each of the 15 kHz and 7.5 kHz options; the channelization for 15 kHz employs 12 subcarriers per resource block, and the channelization for 7.5 kHz employs 24 subcarriers per resource block. The resource blocks for both channelizations have 180 kHz bandwidth (BW).
In LTE, as discussed above, a frame structure is employed that is not flexible, and fixed resource block definitions are used. RB allocation to a user equipment (UE) is performed using an RB allocation indicator bitmap.
Long Term Evolution (LTE) for the most part imposes a 10% guard band usage between LTE useful spectrum and spectrum mask. It would be advantageous to have a more efficient bandwidth utilization, possibly with a reduced or minimized guard band compared to the approach adopted in LTE.